Remove OverrideBean, introduce mechanism to exclude bean/class from automagic scanning

[manovotn]

OverrideBean proved superfluous and can be replaced by alternatives so we can remove that.

Instead, a request was made for a mechanism that will allow to exclude certain classes/beans from automagic discovery and have a mock in place. This only affect @EnableAutoWeld mode.

Issue is covered in PR #59 .